These creams have some chemical that blocks the UV with some capacity, say a factor of 50. Why can’t I apply two layers of this cream to now get a 100 factor equivalent protection?
I asked the chemist at the store and they said it’s not how it works and that the highest protection factor they have is 75 (which was super expensive).
What gives?
Edit: Thank you for those super informative answers.
You still need to pay attention to the weave density and thickness. That “infinity” falls somewhat if you’re wearing the clothing equivalent cheesecloth.
Source: Once got a severe sunburn on a relatively overcast day through a t-shirt that I soon learned hadn’t been thick enough.